Color photographic elements commonly employ silver halide emulsions, with the halide content being dependent on the intended use of the product. In photofinishing processes which use photosensitive paper to produce color prints it is generally desirable to shorten the processing time. One way to shorten the processing time is to accelerate the development rate of the photosensitive paper by increasing the chloride content of the silver halide emulsions, i.e., the higher the chloride content, the faster the development rate.
However, it is often difficult to obtain high, invariant photosensitivity with high chloride emulsions. Typically, high chloride emulsions experience greater fog and emulsion sensitivity changes when stored under high temperature and/or humidity conditions than do low chloride emulsions. The increase in fog and the emulsion sensitivity changes may vary from layer to layer in a photographic element causing increased color imbalance and a loss of quality in the printed material.
The control of fog, whether occurring during the formation of the light-sensitive silver halide emulsion, during the spectral/chemical sensitization of the emulsions, during the preparation of the silver halide compositions prior to coating, or during the aging of such coated silver halide compositions, has been attempted by a variety of means. Thiosulfonates and thiosulfonate esters, such as those described in U.S. Pat. Nos. 2,440,206; 2,934,198; 3,047,393; and 4,960,689 have been used as additives to control fog. Organic dichalcogenides, for example the disulfide compounds described in U.S. Pat. Nos. 1,962,133; 2,440,110; 2,465,149; 2,756,145; 2,866,036; 2,935,404; 2,948,614; 3,043,696; 3,057,725; 3,148,313, 3,226,232; 3,318,701; 3,409,437; 3,447,925; 3,397,986; 3,761,277; 4,243,748; 4,463,082; and 4,788,132 have been used not only to prevent formation of fog but also as desensitizers and as agents in processing baths and as additives in diffusion transfer elements. However, disulfides which inhibit fog formation can also reduce emulsion sensitivity. Organic compounds having a polysulfur linkage comprised of three or more sulfur atoms, and organic compounds having a heterocyclic ring having at least two thioether linkages or at least one disulfur linkage, such as those described in U.S. Pat. No. 5,116,723, have been discussed as suppressing fog and improving raw stock stability when used in combination with nitrogen-containing cyclic compounds.
Photographic elements with a high silver chloride content are also more sensitive to high temperatures during exposure. For example, when the temperature upon exposure rises, i.e., owing to heat from a lamp or the like during printing, the print density changes if the printing conditions are not adjusted to compensate for the rise in temperature. Additionally, an increase in temperature during exposure of the paper often results in a selective increase in speed in one light sensitive layer over another light sensitive layer thereby resulting in an improper color balance in the color print. The photofinishing process must then be adjusted to compensate for this density fluctuation, causing a decrease in efficiency.
Sulfinates have been used for a variety of purposes in photographic elements. They have been described, for example, as storage stability improving compounds in color photographs in U.S. Pat. No. 4,939,072; as anti-staining agents in U.S. Pat. No. 4,770,987; as stabilizers in a direct positive photographic material in U.S. Pat. No. 3,466,173 and as antifoggants in U.S. Pat. No. 2,057,764.
Sulfinates have also been used in combination with other compounds for improving speed and stability in a silver halide photographic element, for example, they have been described for use in combination with thiosulfonate salts and an amine borane in U.S. Pat. No. 5,411,855 and in combination with thiosulfonates and an alkynylamine in U.S. Pat. No. 5,399,479. Sulfinates have also been used, for example, in combination with diamino disulfides to improve storage stability and to reduce high temperature sensitivity during exposure in a silver halide photographic element as described in U.S. Pat. No. 5,356,770; in combination with thiosulfonates to control speed increase on incubation of color photographic materials as described in U.S. Pat. No. 5,292,635; in combination with iodate ions to prevent yellow fog in silver halide materials as described in U.S. Pat. No. 3,615,534; in combination with thiosulfonates for the sensitization of chloride emulsions for color paper as described in JP 3,208,041 and for stabilizing silver halide emulsions as described in U.S. Pat. No. 2,394,198; in combination with labile sulfur compounds in the sensitization of silver halide emulsions as described in U.S. Pat. No. 3,144,336; in combination with small amounts of polythionic acids to stabilize photographic emulsions against fog growth as described in U.S. Pat. No. 2,440,206; and in combination with aromatic or heterocyclic polysulfides in controlling fog growth as described in U.S. Pat. No. 2,440,110.
A need still exists for a method of stabilizing silver halide emulsions against fogging without reducing the sensitivity of the emulsions, thereby preventing a loss in photographic speed. A need also exists for a method of reducing the sensitivity of high chloride emulsions to temperature changes during exposure.